as s e t (Holyport). Adunanza del 26 gennajo I9o8. I. In my paper On (2uinquenodal and Sexnodal Quintic Curves x), I attempted to find the equations of quintic curves which possess four cusps and a node and five cusps respectively, but the results were deficient in that conciseness which is always so desirable and sometimes so difficult of attainment in mathematical investigations. At the end of the paper, I briefly indicated a method which depends upon the theorem that when a tangent cone is

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... awn to a surface, every generator which is a double tangent to the surface is a nodal generator of the tangent cone, and ever), generator which is a stationary tangent is a cuspidal generator of the cone. I propose in the present communication to develope this method. 2. If (% ~, .(, 8) be quadriplanar coordinates referred to a tetrahedron ABCD, the equation of a surface of the n th degree may be written in the binary form